This invention relates to an environmentally friendly, solvent system for the synthesis of poly(amic acid) (PAA) and polyimide (PI) polymers.
Polyimide polymers are useful in a variety of applications, including the manufacture of electronic devices such as semiconductors and display units. PAA polymers are the processible, soluble precursor polymers of PI polymers. Among the many properties of PI polymers that make them favorable for these applications are a high glass transition (Tg) temperature, high thermal stability, high oxidative and hydrolytic stability, good electrical insulation/dielectric properties, strong mechanical attributes, a low coefficient of thermal expansion, and the like. Many PI polymers, and their PAA polymer precursors, are synthesized in solvents now classified as harmful, such as N-methyl-2-pyrrolidone (NMP), N,N-dimethyl acetamide (DMAc), and N,N-dimethyl formamide (DMF).
Much interest exists in finding alternative solvents to replace NMP and like materials in the synthesis of PI and PAA polymers. Such systems, however, need to exhibit not only a better environmental profile, but also comparable cost and performance.